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EP0064789A2 - Interferometer unter Verwendung von optischen Fasern zur Phaseninformationsübertragung - Google Patents

Interferometer unter Verwendung von optischen Fasern zur Phaseninformationsübertragung Download PDF

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Publication number
EP0064789A2
EP0064789A2 EP82200506A EP82200506A EP0064789A2 EP 0064789 A2 EP0064789 A2 EP 0064789A2 EP 82200506 A EP82200506 A EP 82200506A EP 82200506 A EP82200506 A EP 82200506A EP 0064789 A2 EP0064789 A2 EP 0064789A2
Authority
EP
European Patent Office
Prior art keywords
optical
fibre
interferometer according
beam splitter
optical fibre
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP82200506A
Other languages
English (en)
French (fr)
Other versions
EP0064789B1 (de
EP0064789A3 (en
Inventor
Mario Martinelli
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
CISE Centro Informazioni Studi e Esperienze SpA
Original Assignee
CISE Centro Informazioni Studi e Esperienze SpA
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Priority to AT82200506T priority Critical patent/ATE23637T1/de
Publication of EP0064789A2 publication Critical patent/EP0064789A2/de
Publication of EP0064789A3 publication Critical patent/EP0064789A3/en
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Publication of EP0064789B1 publication Critical patent/EP0064789B1/de
Expired legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J9/00—Measuring optical phase difference; Determining degree of coherence; Measuring optical wavelength
    • G01J9/02—Measuring optical phase difference; Determining degree of coherence; Measuring optical wavelength by interferometric methods
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
    • G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
    • G01H9/006—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors the vibrations causing a variation in the relative position of the end of a fibre and another element
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J9/00—Measuring optical phase difference; Determining degree of coherence; Measuring optical wavelength
    • G01J9/02—Measuring optical phase difference; Determining degree of coherence; Measuring optical wavelength by interferometric methods
    • G01J2009/0226—Fibres

Definitions

  • An optical fibre intended as a sensor exhibits intrinsic properties which have a great significance, such as, for instance, the insensitivity to electromagnetic radiations and the great resistance in environments in which the temperature is high.
  • the optical fibre is placed to replace a portion of the optical path of the measuring arm.
  • the optical fibre behaves Like a detector which is extremely sensitive to the environmental noise.
  • Any disturbance which modifies the refractive index or the length of the optical fibre in fact, originates a variation in the phase of the transferred light signal.
  • the disturbance may be originated by a number of causes, such as a localized variation of pressure or temperature, and these situations are extremely likely to occur in industrial installations (for example in the interior of machines or on large structural units).
  • Such variations are summed randomly to the variation of the useful phase, so that the signal-to-noise ratio of the entire system is worsened until rendering the operation impossible even when short optical fibre shanks are used.
  • the effect of an environmental noise is to originate a phase variation in the light signal flowing through the fibre.
  • An objective of the invention is to provide a measurement instrument of- the kind referred to above with the transmission of the beam through an optical fibre, in which the intense degradation of the useful signal, as originated by the keen sensitivity of the optical fi- brew to the environmental noise, is prevented without requiring a thermal and acoustical insulation of the fibre having such dimensions as to become a serious limitation to the practical use of the device concerned.
  • an interferometer which comprises a laser-light emitter which sends a polarized light beam to the input end of a single-mode optical fibre, at the output end whereof a first beam splitter is provided which directs the two resultant beams onto a reference mirror and onto a device producing a reflection of the beam with a modulation of the optical phase which must be detected, respectively, the two beams reflected by the device and by the reference mirror, respectively, being fed back through said first splitter to said output end of the optical fibre to form a composite beam to be sent from said optical fibre input and to a detecting element.
  • FIGURES 1 to 6 of the accompanying drawings show general diagrams of interferometers which operate according to the principles of this invention.
  • FIGURE 1 shows a diagram illustrating a first embodiment of an elementary interferometer made according to the present invention.
  • An interferometer comprises a source 10, of coherent light which sends, a beam towards a beam splitter 11.
  • the laser-light beam flowing through the splitter 11 is sent through an input optical system 12 into a fibre 13 which, via the optical system 14, sends the beam to impinge on the target mirror 15.
  • the beam reflected by the splitter 11 flows through an input optical system 12', a fibre 13' and an optical system 14' to strike a mirror 16.
  • the beam reflected by 16 and flowing through the splitter 11 is summed to the beam reflected by the mirror 15 and reflected again by the splitter 11, to reach the photodetector 17.
  • Such an arrangement of parts could be embodied to achieve the objects of the invention by placing the two optical fibres in a close mechanical connection, so as to have- both these fibres undergoing the same thermal and mechanical stresses which are the source of noise in an environment 18.
  • the noise induced in the branch 13' of reference which is linked to the mirror 16 is the same noise which is induced in the fibre branch 13, so that, on the detector 17, one could have, in theory, a signal stripped of the noise by differential substraction and which, consequently, is only a function of the vibratory motion of the mirror 15.
  • FIGURE 1 has been reported herein only to explain the principles on which the invention is based, but is, apparently, difficult to embody in practice, on taking also into account the problems inherent in subjecting the two branches 13 and 13' to the same cause of trouble which produces an equal noise.
  • the interferometer according to the invention may become practically embodied by the arrangement shown in FIGURE 2.
  • the purpose of the measurement is to detect the vibration amplitude of a target mirror, and, in this embodiment, a laser source 20 sends a beam of vertically polarized light to the polarizing beam splitter indicated at 21.
  • a quarter-wave lamina, indicated at 22, circularly polarizes the light which, via the input optical system 23, is sent into the fibre 24.
  • the light, collected through the optical system 25, is partly reflected by the beam splitter 26 and partly reflected by the reference mirror 27.
  • the light flowing through the splitter 26 is sent to the target mirror 28 which is vibratory and reflects such light to feed it back via.
  • the combined return beams emerge out of the fibre through the optical system 23 and flow again through the quarter-wave lamina 22 so that they reach the polarizing beam splitter 21 with a horizontal polarization and, therefrom, they are fed to the photodetector 29.
  • an analyzer 30 for the signal from the photodetector there can be provided, according to the conventionaL art, an analyzer 30 for the signal from the photodetector.
  • the photodetector 29 thus receives a sensing beam, reflected by the vibratory mirror 28, and a reference beam reflected by the mirror 27, which have flown through the same fibre 24 and thus have undergone the same disturbances which originate the noise that is superposed to the signal consisting of the useful phase variation deriving from the vibrations of the mirror 28 which are actually to be detected.
  • the useful signal is obtained by differential substraction of the noise collected by the transmission line with optical fibres, so that it becomes possible to do away with the shortcomings which are inherent in a too low signal-to-noise ratio, such as would be obtained by adopting the optical fibre transmission in the conventional Michelson interferometer pattern, in which only the useful phase information is transferred through an optical fibres
  • the propagation of the signal is multi-modal, this term being intended to indicate a propagation which takes place with a very great number of wave carriers,- which correspond to as many possible solutions of the electromagnetic field equation in the interior of the "cavity" composed of the fibre core and its coating.
  • phase shift induced by the noise onto the signal involves all the modes, through the different degrees.
  • a single-mode fibre is intended to be, herein, a fibre for which the fibre parameter V fulfils the relationship : less than 2.405 wherein :
  • an interferometer made according to the pattern shown in FIGURE 2 has proven to possess a capability of detection with so high signal-to-noise ratios as to give the detector an indication which is fully comparable with that which would be obtained with a conventional Michelson interferometer, that is, an interferometer having a direct optical path which does not use any optical fibre to transmit the beam.
  • the example shown had the form of a simple vibratory mirror for the reflecting target which originates in the light beam the phase modulation intended to be detected.
  • the sensing beam exiting the splitter 26 can be focussed by an additional optical system to be forwarded to a remote vibratory target having a different degree of reflective power.
  • the reflecting element for the sensing beam can be any known device capable of causing a phase modulation of the reflected beam as a function of a magnitude to be measured.
  • the components of the pattern shown herein can be changed, even though they fulfil the same or equivalent functions, and can be supplemented by additional components known per se in order to achieve the objectives indicated for the invention herein: thus, there have not been described herein because they are conventional, the devices associated to the-detector for measuring and analyzing the interferential phenomena.
  • the optical diagram suggested in FIGURE 2 relates to a configuration in which the reference beam and the measuring beam have the same frequency.
  • This configuration can be dubbed “homodyne” to distinguish it from another pattern, the “heterodyne”, in which it is possible to carry out a modulation as to frequency (or phase) of the reference beam.
  • the latter configuration affords the advantage that detection is permitted, without undetermina- tion, of target vibrations having an amplitude greater than the wavelength of the employed laser light.
  • the heterodyne configuration retains the same principle of noise rejection inherent in the optical fibre shown in FIGURE 2.
  • two beams are fed to the fibre, which have mutually orthogonal polarization.
  • the beam splitter indicated at 26 in FIGURE 2 is replaced by a polarized beam splitter.
  • the reference beam can be modulated either as to phase or as to frequency and can totally be reflected by the mirror 27 placed downstream of the polarized beam splitter and fed back to the fibre input.
  • the measurement beam in its turn, flows unaffected through the polarized beam splitter and is reflected by the target 28 to be fed back to the fibre input.
  • the optical scheme suggested by FIGURE 2 can be modified so as to make the differential operation possible also whenever there are variations in the state.of polarization of the light as induced during the travel of the light through the optical fibre.
  • the optical single-mode fibre undergoes important deformations (radii of curvature in the order of a few centimetres)
  • a rotation of the plane of the polarized light is observed through the fibre.
  • This phenomenon is such as to originate, potentially, undesired variations of .intensity in the pattern of FIGURE 2, since the polarizing beam splitter 21 has transmission characteristics which are a function of the state of polarization of the light.
  • the mismatch between the laser source 20 and the light beam returning from the fibre can be embodied according to the suggestions contained in FIGURES 3 and 4.
  • a diverging optical element D permits that the beam coming from the fibre may be diverged in such a way that only a small fraction of the power is fed back to the source 20.
  • a variation of polarization caused upon the light during the travel through the fibre has thus no bearing on the output signal inasmuch as it affects both the reference signal and the measurement signal.
  • the expedients of FIGURES 3 and 4 and the suppression of the polarized beam splitter 21 prevent a polarization modulation of the signal which is recombined at the fibre input from giving rise to a modulation of the collected intensity.
  • optical scheme suggested in FIGURE 2 can be modified in the portion of the beam splitter 26, while still retaining the same operative principle . More particularly, changes may be introduced which permit that the scattering of light power may be decreased.
  • the beam splitter 26 can be replaced by an integrated beam splitter (also indicated by 26 in the two different-patterns of FIGURES 5 and 6) which is embodied with a coupling technique between single-mode optical fibres.
  • an integrated beam splitter also indicated by 26 in the two different-patterns of FIGURES 5 and 6
  • Such a device while still working under the same operational principle, affords the advantage of making possible the ⁇ splitting of the original beam and the subsequent recombination without losses of power in the beams returning from the mirror 27 and from the target 28.
  • the mirror 27 can be integrated and that the optical fibre integrated beam splitter 26 can be replaced by any equivalent beam splitter constructed with discrete optical elements.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Instruments For Measurement Of Length By Optical Means (AREA)
  • Spectrometry And Color Measurement (AREA)
  • Light Guides In General And Applications Therefor (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
EP82200506A 1981-05-06 1982-04-29 Interferometer unter Verwendung von optischen Fasern zur Phaseninformationsübertragung Expired EP0064789B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT82200506T ATE23637T1 (de) 1981-05-06 1982-04-29 Interferometer unter verwendung von optischen fasern zur phaseninformationsuebertragung.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT21529/81A IT1138312B (it) 1981-05-06 1981-05-06 Interferometro con trasmissione in fibra ottica dell'informazione di fase utile
IT2152981 1981-05-06

Publications (3)

Publication Number Publication Date
EP0064789A2 true EP0064789A2 (de) 1982-11-17
EP0064789A3 EP0064789A3 (en) 1984-05-02
EP0064789B1 EP0064789B1 (de) 1986-11-12

Family

ID=11183149

Family Applications (1)

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EP82200506A Expired EP0064789B1 (de) 1981-05-06 1982-04-29 Interferometer unter Verwendung von optischen Fasern zur Phaseninformationsübertragung

Country Status (6)

Country Link
US (1) US4420260A (de)
EP (1) EP0064789B1 (de)
JP (1) JPS57187627A (de)
AT (1) ATE23637T1 (de)
DE (1) DE3274295D1 (de)
IT (1) IT1138312B (de)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0079944A1 (de) * 1981-05-26 1983-06-01 Gould Inc Interferometer mit optischen fasern.
GB2203259A (en) * 1987-02-26 1988-10-12 Plessey Co Plc Polarisation rotator associated with reflective surface
EP0306227A2 (de) * 1987-09-03 1989-03-08 Western Atlas International, Inc. Faseroptischer Fühler
US4923278A (en) * 1983-10-21 1990-05-08 British Telecommunications Public Limited Company Temperature desensitization of delay in optical fibres
DE3841742A1 (de) * 1988-12-10 1990-06-13 Hueser Teuchert Dorothee Koordinatenmesstaster mit absolutinterferometrischem beruehrungslosem messprinzip
FR2651316A1 (fr) * 1989-08-31 1991-03-01 Univ Leland Stanford Junior Appareil pour detecter une difference de phase entre des premier et second signaux optiques et procede de detection.
EP3683537A1 (de) 2019-01-18 2020-07-22 Fundació Institut Català de Nanociència i Nanotecnologia Verschiebungssensor

Families Citing this family (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4659923A (en) * 1981-03-09 1987-04-21 Polaroid Corporation Fiber optic interferometer transducer
US4652744A (en) * 1982-04-14 1987-03-24 The Board Of Trustees Of The Leland Stanford Junior University Fiber optic sensor for detecting very small displacements of a surface
US4572949A (en) * 1982-04-14 1986-02-25 The Board Of Trustees Of The Leland Stanford Junior University Fiber optic sensor for detecting very small displacements of a surface
US4767210A (en) * 1983-02-24 1988-08-30 British Telecommunications Plc Optical fibre interferometer
GB2144215B (en) * 1983-07-28 1988-06-22 Cise Spa Interferometric detector with fibre-optic sensor
US4714346A (en) * 1986-09-22 1987-12-22 Gte Laboratories Incorporated Frequency chirped interferometric displacement sensors and mechanical translation tips therefor
US4845354A (en) * 1988-03-08 1989-07-04 International Business Machines Corporation Process control for laser wire bonding
US4922095A (en) * 1989-05-11 1990-05-01 Conoco Inc. Method and apparatus for sensing disturbance using fiber-optic polarization rotation
AT396180B (de) * 1989-06-07 1993-06-25 Tabarelli Werner Interferometeranordnung
AT396179B (de) * 1989-06-07 1993-06-25 Tabarelli Werner Interferometeranordnung
AT397307B (de) * 1990-03-02 1994-03-25 Tabarelli Werner Interferometer insbesondere zur längenmessung
CA2013406C (en) * 1990-03-29 1998-06-16 Rene Heon Optical detection of a surface motion of an object
US6485413B1 (en) 1991-04-29 2002-11-26 The General Hospital Corporation Methods and apparatus for forward-directed optical scanning instruments
US6111645A (en) 1991-04-29 2000-08-29 Massachusetts Institute Of Technology Grating based phase control optical delay line
US6501551B1 (en) 1991-04-29 2002-12-31 Massachusetts Institute Of Technology Fiber optic imaging endoscope interferometer with at least one faraday rotator
US6134003A (en) * 1991-04-29 2000-10-17 Massachusetts Institute Of Technology Method and apparatus for performing optical measurements using a fiber optic imaging guidewire, catheter or endoscope
US5383467A (en) * 1992-11-18 1995-01-24 Spectrascience, Inc. Guidewire catheter and apparatus for diagnostic imaging
DE69309953T2 (de) * 1992-11-18 1997-09-25 Spectrascience Inc Diagnosebildgerät
JP2000234959A (ja) * 1999-02-12 2000-08-29 Ando Electric Co Ltd 波長変化測定器及び波長可変光源
US6445939B1 (en) 1999-08-09 2002-09-03 Lightlab Imaging, Llc Ultra-small optical probes, imaging optics, and methods for using same
DE102006017004B3 (de) 2006-04-11 2007-10-25 Airbus Deutschland Gmbh Vorrichtung zur Vermischung von Frischluft und Heizluft sowie Verwendung derselben in einem Belüftungssystem eines Flugzeuges

Family Cites Families (4)

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Publication number Priority date Publication date Assignee Title
GB1373645A (en) * 1972-05-11 1974-11-13 Rank Organisation Ltd Interferometers
JPS5632569B2 (de) * 1973-08-17 1981-07-29
JPS52152741A (en) * 1976-06-15 1977-12-19 Toshiba Corp Optical displacement detector
US4153370A (en) * 1977-12-05 1979-05-08 The United States Of America As Represented By The United States Department Of Energy Microinterferometer transducer

Non-Patent Citations (7)

* Cited by examiner, † Cited by third party
Title
APPLIED OPTICS, vol. 20, no. 9, 1st May 1981, pages 1498-1499 S.C. RASHLEIGH: "Fiber-optic sensors with reduced sensitivity to environmental perturbations" *
APPLIED OPTICS; vol. 17, no. 12, 15th June 1978, pages 1965-1971 M. IIYAMA et al.: "Optical field mapping using single-mode optical fibers" *
OPTICAL AND QUANTUM ELECTRONICS, vol. 10, no. 6, November 1978, pages 533-535 F. PARMIGIANI: "A high sensitivity laser vibration meter using a fibre-optic probe" *
OPTICS AND LASER TECHNOLOGY, vol. 10, no. 1, January 1978, Pages 33-36 R.A. COOKSON et al.: "Mechanical vibration measurements using a fibre optic laser-Doppler probe" *
OPTICS LETTERS, vol. 4, no. 5, May 1979, pages 152-154 R. ULRICH et al.: "Fiber-ring interferometer polarization analysis" *
OPTICS LETTERS, vol. 5, no. 4, April 1980, pages 139-141 D.A. JACKSON et al.: "Measurement of small phae shifts using a single-mode optical-fiber interferometer" *
REVIEW OF SCIENTIFIC INSTRUMENTS, vol. 49, no. 6, June 1978, pages 722-728 M.A. NOKES et al.: "Fiber optic heterodyne interferometer for vibration measurements in biological systems" *

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0079944A1 (de) * 1981-05-26 1983-06-01 Gould Inc Interferometer mit optischen fasern.
EP0079944B1 (de) * 1981-05-26 1987-02-25 Gould Inc. Interferometer mit optischen fasern
US4923278A (en) * 1983-10-21 1990-05-08 British Telecommunications Public Limited Company Temperature desensitization of delay in optical fibres
GB2203259A (en) * 1987-02-26 1988-10-12 Plessey Co Plc Polarisation rotator associated with reflective surface
EP0306227A2 (de) * 1987-09-03 1989-03-08 Western Atlas International, Inc. Faseroptischer Fühler
EP0306227A3 (en) * 1987-09-03 1989-09-06 Western Atlas International, Inc. Fiber optic sensor
DE3841742A1 (de) * 1988-12-10 1990-06-13 Hueser Teuchert Dorothee Koordinatenmesstaster mit absolutinterferometrischem beruehrungslosem messprinzip
FR2651316A1 (fr) * 1989-08-31 1991-03-01 Univ Leland Stanford Junior Appareil pour detecter une difference de phase entre des premier et second signaux optiques et procede de detection.
EP3683537A1 (de) 2019-01-18 2020-07-22 Fundació Institut Català de Nanociència i Nanotecnologia Verschiebungssensor

Also Published As

Publication number Publication date
EP0064789B1 (de) 1986-11-12
DE3274295D1 (en) 1987-01-02
IT8121529A0 (it) 1981-05-06
JPS57187627A (en) 1982-11-18
IT1138312B (it) 1986-09-17
EP0064789A3 (en) 1984-05-02
US4420260A (en) 1983-12-13
ATE23637T1 (de) 1986-11-15

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